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Thread: Model I CRT sounds like an angry snake

  1. #1

    Default Model I CRT sounds like an angry snake

    My Model I monitor sounds like an angry snake inside but only for a bit. It sounds like an angry snake is in there, but it slowly fades away after about 10 minutes. Picture is great. I've got the innards from the crushed one I could canibalize, but the crushed one has two cards on on the main PCB not one, and I haven't checked the snake pit yet.

    Since its a Model I I know there isn't a rubber cap on the anode, I haven't opened it up yet but curious if its just dusty inside or a sign its about to die.

  2. #2
    Join Date
    Oct 2016
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    Cincinnati, Ohio USA
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    Quote Originally Posted by Tibs View Post
    My Model I monitor sounds like an angry snake inside but only for a bit. It sounds like an angry snake is in there, but it slowly fades away after about 10 minutes. Picture is great. I've got the innards from the crushed one I could canibalize, but the crushed one has two cards on on the main PCB not one, and I haven't checked the snake pit yet.

    Since its a Model I I know there isn't a rubber cap on the anode, I haven't opened it up yet but curious if its just dusty inside or a sign its about to die.
    It sounds like arching so I wouldn't use it again until I opened it up and checked it out. I have seen holes burnt into boards from dust caused arching.

  3. #3

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    I'd get a can of duster spray and a small nozzle for a vacuum, then give it a good cleaning. Be careful of the high voltage supply. I've had dust bunnies creating arcing on the CRT envelope, and it sounds like you describe.

  4. #4
    Join Date
    May 2013
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    Williamstown Victoria Australia
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    @Tibs

    Please remember that the Chassis is LIVE (maybe 230 Volts).
    Please unplug from the Mains before cleaning.

    Ray
    If it ain't Broke then PLEASE DONT fix it.
    Procrastinators Unite.
    I keep telling you I am Not Pedantic.

  5. #5

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    Quite possibly the cleanest I have ever seen.

    It's the anode hissing. Solution?

    Thank for the warnings I respect shock hazards like you don't know. No mefal always arm behind never grounded and yeah this sucker is a hot chassis

    PicsIMG_0332.jpgIMG_0330.jpg

  6. #6
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    Corona discharge. Because of the strange nature of the anode connection (no rubber cap) the best I can think of is discharge the tube and wipe down around the area.
    Also, high humidity can cause corona issues.
    = Excellent space heater

  7. #7

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    Ok, I'll discharge it (I've gotten real damn good at this with troubleshooting a 4P card I boogered up recently).

    I've been hit by the anode after only a partial discharge, tickles a little, but I always ensure I have good anti grounding principles.

    Humidity isn't too bad, garage but I have sensors. 79 degrees and 65%.

  8. #8

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    IMG_0331.jpgI took a closeup with flash. I think you are onto something. I see what might be flakes and char.

  9. #9
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    How strange! I've never seen an anode cap without the rubber cover. I wonder if you could ameliorate the situation by covering the bare conductor with a bit of RTV. I probably have a couple of anode caps with rubber shield in my hellbox, if needed.

  10. #10

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    Every model I I have opened has been like this. I thought it was odd too. I'm going to clean first, I have some ATV as well. I suspect there is some oxidation on the conductor that could be contributing to the issue. Once it gets warm it stops, so should be fixable.

    I'll report back tomorrow.

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